1. Field of Technology
The present invention relates generally to a printer and a printer control method, and relates more particularly, to an internal process of a printer when slip printing is resumed after printing has stopped because there is no paper.
2. Description of Related Art
In a printer system having a printer, the printer is typically connected to enable communication with a host computer that generates the print data to be printed and controls printer operations. During printing, for example, the printer executes print control commands received from the host computer to print on slips or roll paper and then output the result.
If a slip that is too small is mistakenly inserted or more print data than can be printed on a single slip is sent to the printer when printing on a slip, an error is generated and printing stops because there is no paper to print on. Such errors are referred to herein as an “out-of-paper error”. When an out-of-paper error occurs, the printer interrupts printing on the slip and waits for a new slip to be inserted.
When a new slip is then inserted, the printer continues printing the unprinted data. When printing thus resumes, the remaining print data that was not printed before the out-of-paper-error occurred and printing stopped is printed on the new slip. The result is that the content that should be printed on a single slip is printed on two slips, and the resulting printed output could be rendered meaningless for the intended purpose if the content thus printed on two separate slips should have been printed on a single slip, such as when printing a sales receipt. When this happens, the same print data must be sent from the host computer to the printer again and reprinted, resulting in wasteful paper consumption. The result is a significant drop in printing efficiency and thus reduced productivity considering the time and effort required to reprint the same content and the printing waste after printing resumes.
JP-A-H11-268384 teaches a printer which receives from the host computer a command instructing the printer what process to execute when the printer returns from an off-line to an on-line state, and the printer thus runs a process determined by the cause of the off-line state when the printer goes back on-line. This printer can thus be prevented from printing the remaining portion of a receipt that will most likely be unusable.
JP-A-2001-180052 teaches a printer which can select whether to store or to automatically discard new print data received while the printer is off-line. When the received data is automatically destroyed with this printer, additional data is not stored in the receive buffer while the printer is off-line, and the receive buffer will thus not become full.
JP-A-H11-268384 and JP-A-2001-180052 describe in detail a process for returning from an off-line state to an on-line state, but are silent regarding the process for recovering from an out-of-paper error. The same process used to return from an off-line state to an on-line state cannot be used when printing stops due to an out-of-paper error because the printer remains in an on-line state and does not switch from an on-line state to an off-line state when an out-of-paper error occurs. Additional consideration is therefore needed to determine the best routine for resuming printing after an out-of-paper error occurs.
It is an object of the present invention to provide a printer and a printer control method allowing to smoothly resuming an interrupted printing operation with no printing waste after printing stops due to an out-of-paper error.